Per Victor's advice I'm posting this here. PEP 520 has been accepted, but without the __definition_order__ attribute. The accompanying comment:
"Note: Since compact dict has landed in 3.6, __definition_order__ has been removed. cls.__dict__ now mostly accomplishes the same thing instead."
The "mostly" is what concerns me. Much like having a custom __dir__ lets a class fine-tune what is of interest, a custom __definition_order__ allows a class to present a unified view of the class creation process. This could be important to classes that employ __getattr__ (or __getattribute__) to provide virtual attributes, such as Enum or proxy classes. With __definition_order__ Enum can display the actual creation order of enum members and methods, while relying on Enum.__dict__.keys() presents a jumbled mess with many attributes the user never wrote, the enum members either appearing /after/ all the methods (even if actually written before), or entirely absent. For example, this class:
class PassBy(Enum):
... value = 1 ... reference = 2 ... name = 3 ... object = name ... def used_by_python(self): ... return self.name == 'name' ... shows this:
PassBy.__dict__.keys()
dict_keys([ '_generate_next_value_', '__module__', 'used_by_python', '__doc__', '_member_names_', '_member_map_', '_member_type_', '_value2member_map_', 'reference', 'object', '__new__', ]) Notice that two of the members are missing, and all are after the method. If __definition_order__ existed it would be this:
PassBy.__definition_order__
['value', 'reference', 'name', 'object', 'used_by_python'] Which is a much more accurate picture of the user's class. -- ~Ethan~ _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com